The diagnosis of 5α-reductase deficiency in infancy

Abstract

The diagnosis of 5α-reductase deficiency in infancy is reported for the first timein three male pseudohermaphrodites from the Dominican Republic. Basal plasma testosterone to dihydrotestosterone ratios were significantly elevated in two of the three affected infants, and increased markedly in all three infants ater administration of hCG. Since urinary etiocholanolone1 to androsterone ratios could not be determined accurately in this age group, the diagnosis of 5αreductase deficiency was confirmed by the finding of elevated urinary tetrahydrocortisol (THF) to 5α-tetrahydrocortisol (5α- THF) ratios, as determined by gas chromatography/mass spectrometry, in the affected male infants compared to those in agematched normal infants.The THF/α-THF ratios, however, were lower in both the normal children and the affected infants, compared to those in older children and adults from both groups, suggesting increased 5α-reductase activity in infancy. The affected infants had THF/5α-THF ratios comparable toratios in adult carrier males and significantly lower than ratios in adult homozygotes. Two of thethree affected infants are related to he large Dominican kindred we studied previously and initially were raised as females but, after parental counseling, were changed to a male sex of rearing.